Typically a respiratory treatment apparatus can provide a patient with a supply of breathable gas (usually air, with or without supplemental oxygen) at a therapeutic pressure or pressures, at appropriate times during the subject's breathing cycle. Such therapies may include continuous positive airway pressure (CPAP), nasal intermittent positive pressure ventilation (NIPPV) and variable positive airway pressure (VPAP), for example. The therapy may be used for treatment of various respiratory conditions including sleep disordered breathing (SDB) and more particularly obstructive sleep apnea (OSA). These apparatus typically require a mask or other patient contact device to direct the delivery of the treatment gas to the respiratory system (e.g., a patient's nares, mouth or both). If such a device is configured to deliver pressures above atmospheric pressure, it may be desirable for a mask to have a design that is both comfortable for the wearer but that can provide an effective seal against mask leaks.